The invention relates generally to a device for controlling communication between a host computer and a plurality of electronic information cards, e.g. so-called IC-cards to be connected intermediately therethrough, and more particularly to an intermediate device adapted to encipher data to be communicated therebetween and readily renew a communication algorithm for enciphering said data.
The so-called IC-card or integrated circuit card comprises, as shown in FIG. 3 of the accompanying drawings, a card-like substrate SUB having a microcomputer MC as a data processor and a semiconductor memory MEM embedded therein, and a plurality of contact points CP which are each connected with the above MC and MEM, and arranged exposedly flush with the outer surface of the substrate SUB.
Recently an IC-card having no electric contacts has been proposed in which a plurality of coils or light receptors are provided instead so as to receive information in the form of high-frequency signals or from a light emitter so as to be stored in the memory.
The IC-card may be electrically connected with the host computer provided with a card connector having contact pins of the number and arrangement corresponding to those of the contact points CP of the card so as to read data stored in the MEM thereof and write new data in the MEM. In general the IC-card is, however, loaded in the intermediate device having card connector as referred to above through a slit formed in the casing wall thereof so that the communication for reading-out and writing-in of the data may be made between the card and the host computer which is linked with the communication control device through a cable.
Such intermediate devices as the IC-card reader/writer are described in many publications, e.g. in U.S. Pat. Nos. 4,724,030, 4,833,310, 4,835,375 given to the applicant or assignee of this patent application, and have been in actual use.
There is a fear, however, particularly in the latter case that the data stored or to be stored in the IC-card is "stolen" by any third party making access to the communication cable. In order to protect the data, various countermeasures have been proposed, among which there is a method where the intermediate device or the IC-card is provided with an ROM storing an algorithm for communication so as to encipher the data which is deciphered in the host computer, or vice versa to be read or written. Such process and apparatus are described in many publications, e.g. U.S. Pat. Nos. 4,544,833 to Michel Ugon in France, 4,453,074 to Stephen B. Weinstein in U.S.A.
Since a ROM is generally combined in the IC-card or the card connector when assembled, the algorithm to be kept in secret may be leaked to a third party through the manufacturer or assembler. Furthermore, when one algorithm is used for a long time, a algorithm may be disclosed to the third party tapping the communication cable in order to decipher the enciphered data.
Thus, it is necessary to often renew the communication algorithm. For that purpose, however, the ROM must be removed from IC-card or the card connector to be exchanged with a new ROM storing another communication algorithm, which necessitates a troublesome work by a skilled person and consequently a considerably high cost.